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NEWS RELEASE: Migratory songbirds are not likely to show fidelity to molting sites

NEWS RELEASE: September 17, 2020

CONTACT: John Alexander, Executive Director, Klamath Bird Observatory, 541‐890‐7067,

Feather wear on a Yellow Warbler.

When playing at home, sports teams usually benefit from home-field advantage. A similar advantage exists among migratory birds that return to the same nesting site year after year to find familiar surroundings, food, and neighbors. The act of returning to the same site—site fidelity—has been documented in songbirds during nesting season for decades; however, what has remained a mystery is whether or not songbirds exhibit a similar site fidelity after the breeding season, during their annual molt, or replacement of feathers. Molting is energetically taxing, which means that birds need a reliable habitat with plentiful food resources and few predators. Scientists have long wondered whether this need similarly pressures birds to return to the same “home-field” molting site year after year.

“Filled circles mark 50 unique constant-effort mistnetting banding sites from the Klamath Bird Monitoring Network in Oregon and California where data used in this study were collected.” (Figueira et. al, 2020)

For the first time, scientists have been able to determine whether migratory songbirds return to both breeding and molting sites; a necessary piece of data to help inform efforts to conserve valuable habitats for birds. In a recent study, a collaborative team of biologists from the Klamath Bird Observatory, USDA Forest Service, Mantiqueira Bird Observatory, and Michigan Technological University’s College of Forest Resources and Environmental Science used 31 years of bird banding data for 16 songbird species from northern California and southern Oregon to estimate the probability of the songbirds returning to the same site year after year to molt.

Findings from this research demonstrated that, while breeding behaviors were strongly associated with site fidelity, the fall molt was not associated with returning to a site for 15 of the study’s 16 songbird species. These results contribute to a growing body of research demonstrating that birds make small-to-large scale movements after the breeding season in search of the food resources necessary to successfully complete their fall molt. Food resources during the fall molt appear less predictable than during spring breeding season, leading to a propensity of songbirds to move and seek out new and food-rich habitats in California, Oregon, and beyond.

Download the full article on The Auk website (subscription required):

Figueira, L., Martins, P., Ralph, C.J., Stephens, J.L., Alexander, J.D., Wolfe, J.D. 2020. Effects of breeding and molt activity on songbird site fidelity. The Auk, ukaa053.

News Release written by Jared Wolfe

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The Klamath Bird Observatory (KBO) is a non-profit organization that advances bird and habitat conservation through science, education, and partnerships. Working in the Pacific Northwest and throughout the ranges of migratory birds KBO emphasizes high-caliber science and the role of birds as indicators to inform and improve natural resource management. KBO also nurtures an environmental ethic through community outreach and education.

The Mantiqueira Bird Observatory (OAMa – Observatório de Aves da Mantiqueira) is an independent nonprofit organization in Brazil for the study and conservation of Atlantic Forest birds. Their missions are to assist in filling in the gaps of the ornithological knowledge in Brazil through long term bird monitoring and scientific research; and to promote stronger connections between science, people and conservation.

Pacific Southwest Research Station (PSW) is one of five regional research stations that make up USDA Forest Service Research and Development. Our scientists collaborate with a range of partners to develop and deliver science and innovative technologies focused on informing policy and land-management decisions to improve lives and landscapes. PSW serves the Forest Service as well as other federal and state agencies, international organizations, Tribes, academia, non-profit groups and the public

The College of Forest Resources and Environmental Science at Michigan Technological University brings students, faculty, and researchers together to measure, map, model, analyze, and deploy solutions. In addition to numerous domestic and international research projects, The College of Forest Resources and Environmental Science leads the world’s longest running predator-prey project focused on the wolves and moose of Isle Royale National Park, and has the 4th highest ranked forestry program in the United States.

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